1. Field of the Invention
The present invention is directed to methods for patterning a surface using contact printing processes that employ a stamp or an elastomeric stencil and a paste.
2. Background
Traditional photolithography methods, while versatile in the architectures and compositions of surface features that can be formed, are also costly and require specialized equipment. Moreover, photolithography techniques have difficulty patterning very large and/or non-rigid surfaces such as, for example, textiles, paper, plastics, and the like. Contact printing methods such as microcontact printing, (see, e.g., U.S. Pat. No. 5,512,131), microcontact molding (see, e.g., U.S. Pat. No. 5,925,259), micromolding in capillaries (see, e.g., U.S. Pat. No. 6,355,198), and the like have been used to pattern a wide variety of substrates, including non-planar and plastic substrates.
Pastes are used frequently to pattern a variety of substrates for applications in which sub-50 μm resolution is not required. Typically, a paste is applied to a substrate by screen printing, spraying, ink-jet printing, or syringe deposition. In particular, pastes comprising an etchant have been used to pattern various metal oxides using screen-printing methods. For example, conductive oxides for display applications can be patterned using an etch paste comprising phosphoric acid or a mixture of iron chloride and nitric acid. Feature sizes of about 50 μm are achievable using a stainless steel screen having a mesh count of about 350 to about 500. However, screen printing has difficulty patterning surface features having a lateral dimension below 50 μm, and can have difficulty patterning features on non-planar substrates. Furthermore, screen printing methods can have difficulty patterning both small- and large-dimension features using the same screen and paste composition.